Spinneret treatment in the manufacture of artificial silk



Patented Nov. 30, 1937 SPINNERET TREATMENT IN THE MANU FACTURE or ARTIFICIAL SILK Johannes Gerardns Weeldenburg, Arnhem,

Netherlands, assignor to American Enka Corporation, Enka, N. C., a corporation of Delaware No Drawing. Application September 8, 1936, Serial No. 99,819. In the Netherlands October Claims. (oi. 18-54) This'invention relates to the manufacture of artificial silk and more particularly to the treatment of spinnerets to prevent clogging of the minute orifices therein during the spinning operation.

In the manufacture of artificial silk according to the wet spinning process, spinnerets or spinning nozzles are employed. These spinnerets are cup-shaped and have a base which contains a plurality of very fine orifices therein. -These orifices function to permit a spinning solution to be extruded therethrough in the form of minute streams, which upon contact with a precipitating or coagulating medium, hardens the same with the resultant formation of hair-like filaments.

The period of extrusion of the viscose solution to form filaments is known as the spinning operation. During this stage difficulties are normally encountered owing to the gradual clogging of the orifices. This results in the manufacture of poor quality yarn, as in order to produce first class commerciaz artificial yarn, it is necessary to provide for uninterrupted spinning of all filaments. The clogging or contamination of the spinnerets can be traced to the presence of impurities of various nature in both the viscose solution and the coagulating bath. Such impurities tend to agglomerate or deposit on the spinneret and partially or entirely block the small orifices therein. It has been noticed particularly that when the coagulating bath contains heavy metal salts, precipitates form within the spinning orifices. Often the foregoing deposits during their initial formation are insufficient to entirely clog the openings but do form on the walls of the orifices sufiiciently to vary the thickness of the individual filaments and such deposits gradually grow to entirely clog the orifices. Consequently, a yarn is formed which has varying characteristics undesirable in the trade.

It has now been determined that the growth of precipitates with the resultant foregoing objections can be substantially prevented or at least considerably inhibited by covering the spinneret surface, including the inside walls of the orifices, with a material of a wax-like type including mineral waxes.

It is therefore the object of the present invention to provide a process for treating spinnerets and an improved article of manufacture as a result of such treatment.

As a further object, the invention contemplates broadly the provision of a material which will prevent the agglomeration or precipitation, on

the spinnerets, of impurities in the spinning solution and precipitating bath which would otherwise cause clogging or at least the decrease in size of the openings or orifices within the base of the spinnerets.

In carrying out my improved process the spinnerets to be'treated .are first cleaned and made ready for covering the same with a wax-like material. A smallquantity of paraffin or other mineral wax dissolved in a suitable solvent is applied to the surface of the spinneret, including the walls and base containing the openings, either by immersion of the spinnerets therein or by spraying the solution-thereon. The spinnerets are then freed from excess treating liquid by cen trifuging and. thereafter dried. 'As a final step the coated spinnerets are heated to such anex tent that the wax-like layer again meltsjand forms an even layer over the entire surface contacted. g

A particularly suitable material for covering the spinnerets is a paraflin of comparativelyhigh melting point; for example, one which melts between 68 and 72 C; However, it is also contemplated to use waxes of the Ozocerite type, ceresine and similar materials. The solvent for the wax must be one in which the waxy material is extremely soluble and which has a comparatively low boiling point so that it will evaporate below the melting point of the waxy material. .An example of a desirable solvent is petroleum ether.

The concentration of the solution must be so chosen that after immersing and centrifuging the spinnerets and evaporating the solvent therefrom, a desirable thickness of the layer of covering material is obtained.

A specific example of applying the present invention is as follows: 0.5% solution of parafiin is dissolved in petroleum ether; or if desired, ben-' zene (CsHs) may be employed as the solvent. The clean spinnerets are immersed in the solution for approximately five minutes, after which they are centrifugedor hydroextracted and heated in an oven until the paraffin is molten. The

spinnerets are then cooled and ready for use.

Whereas the invention has been described applying specific solvents and solutes, it is within the scope of my invention to employ a covering material for spinnerets which will not impair the spinning operation, while at the same time, prevent the formation of deposits on spinnerets which would otherwise clog the orifices therein.

What I claim is:

1. In the manufacture of artificial silk a rccess of treating spinnerets which comprises covering the spinnerets with a wax-like material and. retaining the same thereon to inhibit the formation of deposits around the orifices of the spinnerets during the spinning operation.

2. In the manufacture of artificial silk a process of treating spinnerets which comprises covering the spinnerets with a mineral wax and retaining the same thereon to inhibit the formation of deposits around the orifices of the spinnerets during the spinning operation.

3. A process for treating spinnerets employed in the manufacture of artificial silk which comprises forming a solution of a wax-like material, applying said solution to the spinnerets to thereby coat and render the same free of deposits which would otherwise form on the spinnerets-during the spinning period.

4. A process for treating spinnerets employed in the manufacture of artificial silk which comprises forming a solution of a mineral wax, applying said solution to the spinnerets to thereby coat and render the same free of deposits which would otherwise form on the spinnerets during the spinning period. v

5. A process of treating spinnerets which comprises cleaning a plurality of spinnerets, immersing the same in a solution of parafiln dissolved in petroleum ether, removing the coated spinnerets and centrifuging the same to eliminate the excess liquid and thereafter heating the spinnerets, whereby the solvent is evaporated and the paraffin forms an even layer over the entire surface of the spinnerets.

6. A process for treating spinnerets to prevent the formation of objectionable deposits within the orifices thereof which comprises coating the spinneret surface with paraffin and thereafter effecting an even coating over the entire surface.

'7. A process for treating spinnerets to prevent the formation of objectionable deposits within the orifices thereof which comprises coating the spinneret with an organic solution of a mineral wax which contains small quantities of high melting parafiin and subsequently centrifuging and heating the spinneret above the melting point of the coating material.

8. A process for treating spinnerets which comprises applying a 0.5% solution of paraflin dissolved in petroleum ether to the spinnerets, maintaining the said solution in contact with the spinneret surface for approximately five minutes, thereafter centrifuging the spinnerets to remove the excess liquid and heating the spinnerets to a temperature which will evaporate the solvent and effect an even layer of paraffin over the spinneret surface.

9. A process as defined in claim 8 which further comprises heating the spinnerets to a temperature within a range of 68 to 72 C.

10. A process of treating spinnerets to prevent the orifices therein from becoming clogged as a result of the formation of deposits around the walls of the orifices which comprises covering the spinneret surface with a solution of a mineral wax dissolved in an organic solvent, removing and centrifuging the spinneretto eliminate the excess liquid, effecting a uniform layer of the mineral wax by heating the spinneret above the evoporation temperature of the organic solvent whereby the spinneret surface including the walls of the orifices are coated with a thin layer of mineral wax.

JOHANNES GERARDUS WEELDENBURG. 

